1. Field of the Invention
The present exemplary embodiment relates to the chemical arts. It finds particular application in conjunction with a device for adjusting the pH of a liquid, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
2. Discussion of the Art
The pH of any solution is one of the most important properties of that solution. Therefore, in any wet laboratory context, be it in a research, educational, or industrial laboratory, it is often desirable for the pH of the solutions and liquid reagents used to be controlled and known. Before any solution is used as a reagent, or as a sample for some measurement, its pH is often adjusted to a specific value. Also, there are certain processes that proceed only at an optimum pH.
The pH adjustment of a target solution is currently carried out by volumetric addition of a suitable acid and/or base solution until the pH reaches the desired value or range. This is achieved in most settings manually, but other convective schemes such as the use of a piston burette or a syringe also exist.
The actual pH during adjustment is generally measured or monitored to make sure that the end pH reached is acceptable. A predetermined amount of addition of an acid or base to a sample is often unsatisfactory since, even for well know solutions, variability in buffer capacity, dependence on pH, absorbed air carbon dioxide, and many other factors can affect how much the pH shifts upon the addition of a known amount of acid or base to a known volume of the sample. A feedback system may be employed, in the form of a pH measuring electrode, a pH indicator, or some other means.
Besides acid or base addition and pH assessment, it is common for stirring to be carried out after each addition, to ensure homogeneity of the solution before assessing the pH. This is generally performed manually, for example, by shaking the sample container or by mixing with a glass rod, or the like. Magnetic stirrers and vibrated platforms are also used.
The buffer capacity of pH can vary over a very large range (orders of magnitude). As a result, it is common for lab personnel to have available to them a number of acid and base solutions of various strengths to adjust pH. The adjustment of pH is generally performed by a trial and error process. It is not uncommon to overshoot the intended pH after multiple additions of an acid or base. This iterative process can go on over many steps to finally reach an acceptable pH value. This takes time and may result in dilution of the target solution which is generally undesirable, especially in small volumes.
The present application provides a new and improved system and method for adjustment of pH which overcomes the above-referenced problems, and others.